Protections
91
7.9 SHORT CIRCUIT ALARM
If the Short Circuit alarm is enabled, the controller begins following the IDMT ‘curve’. If the Trip is
surpassed for an excess amount of time the Alarm triggers (Shutdown or Electrical trip as selected in
Action).
The higher the Short Circuit, the faster the trip. The speed of the trip is dependent upon the fixed
formula :
T = K x 0.14 / ((I / I
s
)
0.02
-1)
Where: T is the tripping time in seconds (accurate to +/- 5% or +/- 50ms (whichever is the greater)
K is the time multiplier setting
I is the actual current measured
Is is the trip setting value
The settings shown in the example above are a screen capture of the DSE factory settings, taken
from the DSE Configuration Suite software.
I
S
(Trip setting
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